1. Field of the Invention
This present invention relates to an antenna, and more specifically to a dual-band antenna mainly applied in a notebook computer.
2. The Related Art
Portable electronic devices, such as notebook computers, are usually equipped with antennas for wirelessly transmitting information. In general, there are two types of the antennas mainly used in the notebook computers, planar inverted-F antennas and monopole antennas. However, since the frequency band, antenna gain and radiating efficiency of the planar inverted-F antenna are all in direct proportion to the volume of the planar inverted-F antenna, a dual-band antenna made up of the planar inverted-F antennas is tend to have narrower frequency bands under the condition of miniaturization and complanation, partly covering the frequency bands of 5.2˜5.8 giga-hertz (GHz) and 2.4˜2.5 GHz accordant with the standard of IEEE802.11a/b in wireless local area network (WLAN). Therefore, the planar inverted-F antennas cannot meet the present demands of users. The monopole antenna, though, has a broad frequency band, it has to provide a bigger grounding portion for being in use. So the wide spread use of the monopole antenna is meanwhile limited because of the small available space of the notebook computers.